We present a mirror model moving in the quantum vacuum of a massive scalar field and study its motion under infinitely fluctuating quantum vacuum stress. The model is similar to the one in [Q. Wang and W. G. Unruh, Motion of a mirror under infinitely fluctuating quantum vacuum stress Phys. Rev. D 89, 085009 (2014).], but this time there is no divergent effective mass to weaken the effect of divergent vacuum energy density. We show that this kind of weakening is not necessary. The vacuum friction and strong anticorrelation property of the quantum vacuum are enough to confine the mirror’s position fluctuations. This is another example illustrating that while the actual value of the vacuum energy can be physically significant even for a nongravitational system, and that its infinite value makes sense, but that its physical effect can be small despite this infinity.

• Received 24 June 2015

DOI:https://doi.org/10.1103/PhysRevD.92.063520